By use of parallel chemistry coupled with physicochemical property design, a series of selective kappa opioid antagonists have been discovered. The parallel chemistry strategy utilized key monomer building blocks to rapidly expand the desired SAR space. The potency and selectivity of the in vitro kappa antagonism were confirmed in the tail-flick analgesia model. This model was used to build an more ..

Abstract: By use of parallel chemistry coupled with physicochemical property design, a series of selective kappa opioid antagonists have been discovered. The parallel chemistry strategy utilized key monomer building blocks to rapidly expand the desired SAR space. The potency and selectivity of the in vitro kappa antagonism were confirmed in the tail-flick analgesia model. This model was used to build an exposure-response relationship between the kappa K(i) and the free brain drug levels. This strategy identified 2-methyl-N-((2'-(pyrrolidin-1-ylsulfonyl)biphenyl-4-yl)methyl)propan-1-amine, PF-4455242, which entered phase 1 clinical testing and has demonstrated target engagement in healthy volunteers. (PMID: 21744827)